Rapid self-assembly of robust ultrathin ionogel films for high-performance bioelectronics

Ionogels, polymer networks infiltrated with ionic liquids (ILs), are promising for flexible electronics but face trade-offs among mechanical robustness, ultrathin form factors, and scalable fabrication. We present an IL-induced self-assembly strategy enabling the rapid formation of ultrathin polyvinyl alcohol (PVA) ionogel films. Upon contact with ILs, PVA chains spontaneously organize into a robust, noncovalently cross-linked network, achieving ultrafast conversion (<5 s) of viscous precursors into films with tunable thickness (13 to 103 μm). The resulting ionogel films combine high tensile strength (9.69 MPa), toughness (35.93 MJ m^-3), good ionic conductivity (0.2 S m^-1), and excellent environmental stability. This approach allows in situ formation of conformal ionogel coatings on complex, nonplanar surfaces, yielding seamless skin-device interfaces that retain stable functionality under repetitive deformation. Ionogel-based bioelectrodes capture diverse electrophysiological signals with high fidelity while serving as stretchable substrates for printed circuits and electrode arrays. Compatibility with diverse ILs highlights the versatility of this rapid, scalable approach for fabricating ultrathin ionogels with broadly tunable properties.